Character mistake: Tom Mason makes references to smaller armies defeating larger ones, of which history is rife with examples. He cites the Scottish defeating 'the British' at the Battle of Stirling Bridge. 'The British' did not exist at that time. The Scots administered a beating against the English in the Scottish War of Independence, against the Earl of Surrey, under Edward I. Someone with his level of knowledge would know that.
Map of the Seven Knights - S5-E10
Factual error: The Czech crime database (which appears to be an official Czech database) is headed 'Czechoslovakia'. Czechoslovakia has not existed since the Czech Republic and Slovakia separated in 1993 and neither country uses the term any more.
Revealing mistake: The swords Jayden and Dekker use often bend when striking each other, revealing they are rubber blades and not metal.
Continuity mistake: At the waterfall, after jumping off the cliff and into the water, Skye leads Josh to the rock carvings. Josh's wet hair keeps changing position from being completely slicked back, to partially covering his forehead, to being completely forward over his brow.
San Junipero - S3-E4
Continuity mistake: Near the end, Yorkie gets into a red left-side drive convertible, then is seen driving on highway in the same car but with right side drive. Following scenes are of a left-side drive car. (00:58:00)